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Troubleshooting the Murphy 518PH Tattletale® by Enovation Controls

Understanding Relay Trips And Grounding Issues

Written by
The MurCal Blogster
Published on
July 26, 2024 at 10:08:05 AM PDT July 26, 2024 at 10:08:05 AM PDTth, July 26, 2024 at 10:08:05 AM PDT

When a customer encounters an issue with their 518PH Tattletale®, particularly if the reset button pops out, it's often a grounding problem that has caused the relay to trip. Understanding the wiring and function of the 518PH Tattletale can help diagnose and resolve this issue quickly.


Understanding the 518PH Tattletale®Contacts


The 518PH Tattletale® by Enovation Controls is equipped with several key contacts, each serving a specific function:


-(G) Ground: Provides a grounding point for the device.

-(NC) Normally Closed: This contact remains closed until an alarm condition occurs.

-(SW1) Switch 1: One of the switch inputs.

-(SW2) Switch 2: The second switch input.

-(B) Battery +(or “feet”): Supplies positive battery voltage to the device.


The 518APH Tattletale® by Enovation Controls is equipped with similar ones:


-(G) Ground: Provides a grounding point for the device.

-(NC) Normally Closed: This contact remains closed until an alarm condition occurs.

-(NO) Normally Open: This contact remains open until an alarm condition occurs.

-(SW1) Switch 1: One of the switch inputs.

-(SW2) Switch 2: The second switch input.

-(B) Battery + (or “feet”): Supplies positive battery voltage to the device.


The 518 series Tattletale® requires power to be energized (button in), where similar Tattletales® are latched in mechanically. These conditions must be present for the 518 to remain energized;


1. Battery VDC between the B (battery +) and G (ground) terminals.

2. SW1 and SW2 connected; Either using the included metal jumper for non closed loop, or wiring Swichgages for closed loop (see wiring instructions). 



Two Gauge Scenario: Series Configuration for Pressure and Temperature


In applications that use pressure and temperature gauges, these switch gauges can be configured in series with a common fault detection rather than in a closed loop. 

To achieve this configuration, install the supplied jumper between (SW1) and (SW2) to allow the two contacts to act as one so the switch gauges will maintain ground. 


Detecting Fault Conditions


When either of the two gauges (pressure or temperature) rises above or falls below the user-defined set points, the relay within the 518PH tattletale will trip. This action results in the following:


-Alarm or Shutdown: The relay tripping will trigger an alarm or shutdown procedure to protect the equipment.

-Reset Button: The reset button will pop out, signaling that a fault condition has been detected.


Grounding Issues


Grounding problems are a common cause for relay trips in the 518PH Tattletale. Ensuring proper grounding can prevent unnecessary alarms and equipment shutdowns. Here are some tips to address grounding issues:


-Check Connections: Ensure all ground connections are secure and free from corrosion or damage.

-Verify Continuity: Use a multimeter to verify continuity in the grounding circuit.

-Inspect Jumper: verify the jumper between (SW1) and (SW2) is properly installed and intact.



Properly understanding the wiring and function of the 518PH Tattletale® by Enovation Controls is crucial for troubleshooting issues like unexpected relay trips and grounding problems. By configuring the switch gauges in series and ensuring solid grounding connections, you can maintain reliable operation and prevent unnecessary alarms or shutdowns. If the reset button pops out, check these aspects first to diagnose and resolve the issue effectively.


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For Technical Support, Please Call Us At 661-272-4700, Contact Us Or Email Us At Sales@Murcal.Com

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